Composite cathode material for lithium ion battery and preparation method thereof

A technology for lithium-ion batteries and negative electrode materials, applied in electrode manufacturing, battery electrodes, circuits, etc., can solve the problems of poor performance of electrode materials, achieve low charge and discharge potential, high Coulombic efficiency, and overcome low conductivity

Inactive Publication Date: 2011-04-06
BAOWU CHARCOAL MATERIAL TECH CO LTD +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] Therefore, in order to solve the problem of poor performance of existing lithium battery electrode materials, the purpose of the present invention is to make full use of the respective advantages of needle coke and Si to provide a composite negative electrode material with high lithium intercalation capacity and excellent performance and its preparation method

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0024] Coal-based needle coke was pulverized to an average particle size of 7 μm, graphitized at 2600 ° C for 0.5 h in an argon atmosphere, and made into an electrode sheet. The first Coulombic efficiency was measured to be 85%, and the first discharge capacity was 350 mAh / g. After 150 times of repeated charge and discharge, the discharge capacity drops to 297mAh / g, and there is a stable charge and discharge potential platform at 0.2-0.4V.

[0025] Mix Si with an average particle size of 25nm and the above-mentioned needle coke at a mass ratio of 15:85, put them in a ball mill for mixing and ball milling for 10 hours, and make an electrode sheet. The first Coulombic efficiency is 87%, and the first discharge capacity is 2100mAh / g, there is a stable charge-discharge potential platform at 0.2-0.5V, but the discharge capacity decreases to 800mAh / g, 464mAh / g, 283mAh / g and 225mAh / g, it can be seen that the battery negative electrode material made of graphitized needle coke and Si ...

Embodiment 2

[0028] Coal-based needle coke was pulverized to an average particle size of 7 μm, graphitized at 2800 ° C for 0.5 h in an argon atmosphere, Si and graphitized needle coke with a mass ratio of 2:8 were placed in a ball mill for mixing and ball milling for 10 h to produce After the electrode sheet, the measured first Coulombic efficiency is 90%, the first discharge capacity is 1900mAh / g, and there is a stable charge-discharge potential platform at 0.2-0.5V, but 50 times, 100 times, 150 times, 200 times of repeated charging and discharging Afterwards, the discharge capacities were respectively reduced to 600mAh / g, 427mAh / g, 260mAh / g and 200mAh / g.

[0029] The above Si / needle coke composite electrode material was placed in a chemical vapor deposition furnace, with toluene as the carbon source, vapor deposition was carried out at 1000 °C under a nitrogen atmosphere for 2 h, and then the surface was chemically modified at 450 °C for 2 h under a hydrogen atmosphere. After the prepare...

Embodiment 3

[0036]The petroleum-based needle coke was pulverized to an average particle size of 15 μm, graphitized at 2600 °C for 1 h in an argon atmosphere, and Si (average particle size 15 nm) with a mass ratio of 2:8 and the graphitized needle coke were placed in a ball mill Mix ball mill for 10h.

[0037] The above Si / needle coke composite electrode material was placed in a chemical vapor deposition furnace, with ethane as the carbon source, and vapor deposition was carried out under a nitrogen atmosphere at 1000 ° C for 2 h. The thickness of carbon deposited on the surface of the particles was 5 nm, and then carbon monoxide Surface chemical modification was carried out under atmosphere for 3h. That is, the Si / needle coke composite negative electrode material for lithium ion batteries is obtained. After the obtained material was made into an electrode sheet, its initial Coulombic efficiency was measured to be 89%, and its initial discharge capacity was 1905mAh / g. After 50, 100, 150, ...

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Abstract

The invention provides a composite cathode material for a lithium ion battery and a preparation method thereof. The composite cathode material of the invention comprises nano Si and graphitized needle coke; the average grain diameter is 5-15 microns; and the mass content of the nano Si in the composite cathode material is 5-30 percent. The composite cathode material of the invention not only improves the lithium embedding capacity of needle coke by 2.5-5 times but also overcomes the defects of low conductivity and easy volume expansion of silicon with high lithium embedding capacity. The preparation method of the invention comprises the following steps of: grinding the needle coke; carrying out graphitization treatment at argon atmosphere; mixing with nano silicon; depositing carbon on the particle surface of Si/needle coke; and then carrying out surface treatment on the composite cathode material. On one hand, the preparation method of the composite cathode material solves the problem of lower lithium embedding capacity of a single needle coke cathode material, on the other hand, the preparation method of the composite cathode material overcomes the defects existing in the nano Si used as the cathode material.

Description

technical field [0001] The invention relates to a negative electrode material for a lithium ion battery and a preparation method thereof, in particular to a Si / needle coke composite negative electrode material for a lithium ion battery and a preparation method thereof. Background technique [0002] With the depletion of fossil fuels, the energy crisis has become the focus of global attention. Therefore, the development of new energy is currently listed as an important strategic industry for countries to get rid of economic recession and seize the commanding heights of future development. In the field of new energy, lithium-ion batteries have been widely used in portable electronic appliances such as cameras, mobile phones, and notebook computers due to their excellent characteristics such as high energy density, high power density, good cycle performance, environmental friendliness, structural diversity, and low price. widely used. In the past ten years, due to the rapid de...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/36H01M4/38H01M4/04
CPCY02E60/12Y02E60/10
Inventor 张秀云刘春法詹亮叶冉凌立成
Owner BAOWU CHARCOAL MATERIAL TECH CO LTD
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